1. Field of the Invention
The present invention relates to a Coordinated Multi-Point (CoMP) transmission. More particularly, the present invention relates to a method and an apparatus for selecting a base station for CoMP communication in a cell clustering group of a wireless communication system.
2. Description of the Related Art
Techniques for managing inter-cell interference may be divided largely into interference randomization, interference cancellation, and interference coordination/avoidance. The interference randomization technique does not allow packets of other users to affect a channel decoding process by means of a cell-specific scrambling and a cell-specific interleaving. The interference cancellation performs Successive Interference Cancellation (SIC) based on the encoding packet, or removes the interference using multiple antennas or multiple resources based on the symbol. The interference coordination is based on cell planning or frequency planning, and changes a frequency reuse coefficient according to a terminal's location in the cell or the interference. The interference coordination may coordinate the resource allocation according to directionality of the interference.
In regard to the interference coordination scheme, a method for changing the resource allocation status per cell is suggested so as to adapt to environmental changes such as cell layout, varying traffic condition, and cell addition/deletion. The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard designates high interference or low transmit power with respect to a specific resource per cell. In addition, an Overload Indicator (OI) informing of a considerable interference situation for the uplink is defined, wherein each base station informs its neighboring base stations of the information.
In addition to the above-stated inter-cell interference cancellation techniques, Coordinated Multi-Point (CoMP) transmission techniques are suggested. According to the CoMP transmission/reception, one User Equipment (UE) communicates with a plurality of e-Node Bs (eNBs) so as to raise the throughput in the cell boundary or the throughput of the whole system. In the CoMP transmission/reception, while the coordinated communication of all base stations around a specific UE is the best way to raise the throughput, its applicability is quite low because of computational complexity and scheduling issues among the base stations. In this regard, a cell clustering method is suggested, which performs the CoMP communication by gathering some base stations around the specific UE into one group (hereafter, referred to as a CoMP set).
A conventional cell clustering method is practicable by lowering the complexity in the ideal CoMP transmission/reception environment. However, there may coexist a plurality of UEs for the CoMP transmission/reception and a plurality of UEs not supporting the CoMP transmission/reception within the cell.
Therefore, a need exists for a method and an apparatus for selecting a base station to raise system efficiency in CoMP transmission after cell clustering in an uplink of a wireless communication system.